In the inkjet printers of this kind, when ink is discharged onto the recording medium, an influence of wave-like deformation such as crumpled paper (hereinafter called cockling) must be eliminated as much as possible, and an interval between a recording medium and a recording head must be maintained constant. Furthermore, a paper floating from above a platen toward a direction of the head must be prevented. In order to solve the problems mentioned in the foregoing, an inkjet recording device is disclosed in Japanese patent laid open publication H9-48161 wherein a plurality of concave portions and a plurality of convex portions are provided on an upper portion of the platen, and furthermore, a paper holding plate is disposed to be in contact with the plurality of concave portions, and projections are provided on the paper holding plate at positions corresponding to the plurality of concave portions. Furthermore, in Japanese patent laid open publication H7-256955, a printer mechanism provided with ribs on an upper surface of the platen as a countermeasure of cockling is disclosed.
Furthermore, generally, as a paper feeding mechanism for inkjet plotter (printer), for example, as being disclosed in Japanese patent laid open publication H9-11566, [mechanism wherein a recording paper is retained under pressure by means of a main roller and a holding roller of drum type, and is sandwiched by means of a subroller and a spur type roller, and thus, the floating of the paper is prevented and is carried toward a discharge outlet along an upper position guide plate while it being in tight contact] is employed.
Moreover, in inkjet plotter (printer) of pinch roller type has been developed wherein the paper is caused to make a tight contact on a flat drafting member formed with a plurality of ventilation holes by means of a suction force of a suction device, and both sides of the paper are sandwiched by means of a drive roller and a pinch roller, and the paper is fed in a predetermined X-axis by the rotation of the drive roller while the inkjet type recording head is caused to reciprocate in a Y-axis direction to perform a recording on the paper by means of the recording head. Furthermore, a mechanism is known wherein an unevenness (jogs) guide unit consisting of a plurality of convex stripes and adjacent concave grooves is provided on a base plate of the drafting member, and the recording is carried out on the paper which is disposed on the unevenness guide unit, and the paper is under pressure at a lower stream of a recording position by means of the spur type roller thereby preventing the paper floating.
In order to prevent the paper floating by providing convex portions or ribs on the platen or by positioning a portion of the paper that is curved downward at the concave portions formed between the convex portions or the ribs, there is a necessity of forcing the lower surface of the paper to contact the convex portions or the ribs. The conventional device has a construction wherein the projections of the paper holding plate are caused to contact the paper before it comes to the printing unit or the paper is caused to make a curve by the paper guide before it comes to the printing unit, and the paper is caused to contact the ribs by means of the pressure. However, the projections of the paper holding plate cannot be disposed in the vicinity of a printing area so that the paper cannot be caused to contact the convex portions. Also, a method of causing the paper to contact the ribs by taking advantage of the curve of the paper cannot obtain a sufficient pressurizing force.
Furthermore, in case of using the drafting member having a flat perforated paper support surface, the paper that absorbs the ink at the time of recording inflates. The suction device causes problems such as the inflated portion is not adsorbed onto the paper support surface by vacuum force, or the paper floating occurs that causes the recording head rubs on the paper. In addition, when the paper is caused to be in direct contact with the spur type roller, an adverse influence occurs on the quality of picture and the spur type roller stains the paper after recording.
An object of the present invention is to solve the foregoing points.